Antenna arrays for enhanced estimation of azimuth and elevation

We address the estimation of the direction(s) of arrivals (DOA) of emitting sources. In a number of applications, a priori knowledge about the source location is available so that the possible DOA values can be restricted to a limited angular sector. In addition to a subsequent complexity reduction of the DOA estimation algorithm (especially that of the MUSIC algorithm), this relieves from the need to use antenna arrays (often circular arrays) with uniform accuracy. After developing a simplified Cramer-Rao bound, alternative array configurations are proposed. While these do not provide a uniform error in all directions, they improve the performance within a given sector, the width of which can be chosen as large as desired.